Under the recent trend to economize energies, attempts are being made to develop motors with a most important theme to improve efficiencies. A most difficult problem in these attempts to develop motors which have improved efficiencies lies in realization of windings which are formed at high spatial occupation ratios in stator slots.
A stator of a motor is manufactured by winding a wire around a cylindrical stator core which is subjected to an insulating treatment. However, the cylindrical form of the stator core makes a winding work tedious, and in winding works using nozzles for example, forms of windings and slots are restricted by shapes of the nozzles and driving loci of the nozzles, resulting in limited spatial occupation ratios of windings. To solve this problem, there has been disclosed a method to create a space which facilitates control of winding around a winding slot by winding a wire after coupling a plurality of core segments which are to compose a stator so as to form a serial body. (Japanese Patent Application Laid-Open No. 8-19196).
The serial body of core segments is composed, for example, of core segments 11 which are punched out as integral cores, laminated and coupled by way of easily deformable thin links 14 as shown in FIG. 4 or core segments 11 which consist of core sheets 10 punched out independently and laminated, have concave grooves 15 and convex pieces 16, and are assembled into a serial body by coupling the concave grooves 15 with the convex pieces 16 so as to be rotatable around coupled portions as shown in FIG. 5.
At a stage to form an annular body after winding a wire around a serial body 13 of core segments, a length of a connecting wire which connects coils of the core segments constitutes a factor important for forming the annular body. When the connecting wire is too long, it is overabundant and constitutes a cause for troubles such as seizure of the connecting wire at a stage to complete a motor. If it is too short, in contrast, it constitutes a cause for troubles such as wire breakage at a stage to form the annular body.
Further, it is practiced, as an ordinary method for winding a wire around the serial body 13 of core segments, to wind a coil for each phase around the core segments 11 sequentially one by one. FIG. 7(a) shows a conventional example to wind a wire around a serial body of core segments specified for three phases. After keeping a winding start terminal wire 22 on a terminal or the like arranged on No. 1 core segment, a coil for phase A is wound around Nos. 1, 4, 7 and 10 core segments, and a winding end terminal wire 22 is kept on a terminal or the like arranged on the No. 10 core segment to complete the winding of the coil for the phase A. Wires for phases B and C are wound in the similar procedures. Since the wires for the three phases are wound in series sequentially as described above, this winding method requires terminal treatments six times in total or a large number of winding steps.
The present invention provides a method to manufacture a stator by coupling a plurality of core segments so as to form a serial body of core segments and rounding the serial body into an annular body, which does not allow a connecting wire to be too long or too short between the core segments at a stage to round the serial body of core segments into the annular body as well as a stator which secures an optimum length of a connecting wire and a winding method which minimizes a number of steps to wind a wire around a serial body of core segments.